Various types of building assembly kits are known in the prior art. However, what is needed is a building assembly kit with roof ring having an open-ended plurality of hollow cuboid tube joints radially disposed around an open center of a roof ring and a plurality of parallelepiped strut members disposed between each of the plurality of cube joints, each of said cube joints and strut members disposed to interconnect endwise with a plurality of extant rafters, said rafters thence interconnectable with a plurality of top brackets disposed to interconnect each of said plurality of rafters at a juncture between a pair of horizontally disposed extant wall top beams and a vertically oriented corner post, said corner post connected at a juncture of a pair of base runners at a base bracket, wherein a structure is expediently erected by inserting each rafter, wall top beam, corner post, and base runner into a corresponding tube joint, top bracket, and base bracket